Steam generating plant



Sept. 17, 1963 s. G. BAUER Erm.

STEAM GENERATING PLANT Filed March 26, 1959 United States Patent Ofce 3,103,917 Patented Sept. 17, 1963 3,103,917 STEAM GENERATING PLANT Stefan George Bauer, Hilton, and Derek Howard Jubb,

Manningham, Bradford, England, assignors to Rolls- Royce Limited, Derby, England, a British company Filed Mar. 2.6, 1959, Ser. No. 802,118 Claims priority, application Great Britain Apr. 17, 1958 7 Claims. (Cl. 122-1) This invention comprises steam generating plant of the class comprising a heater and steam generating means wherein feed water is evaporated by steam which has been superheated in the heater. Such steam generating plant will be referred to as being of the class specified.

According to the present invention, steam generating plant of the class specified has steam generating means comprising heat exchange apparatus wherein water is evaporated and the steam so generated is superheated by part of the steam superheated in the heater, and a sonic or supersonic nozzle through the steam so generated and superheated is expanded, the steam issuing from the nozzle having added to it the superheated steam which has been used for effecting the evaporation, and the resulting quantity of steam being then compressed and being fed to the heater to be heated.

Preferably a venturi device is provided to alord the nozzle and also a divergent path when some compression occurs, the steam used for evaporation being injected at the venturi throat. The nozzle preferably discharges into a parallel mixing section wherein the major pressure rise occurs, and which leads to the divergent path when provided, in which case excess velocity head is recovered in the divergent section.

Water may be sprayed into the steam between the outlet of the venturi device and the heater to reduce its degree of superheat.

One form of steam generating plant of the class specified and embodying the invention will now be described with reference to the accompanying drawing.

The plant comprises a heater 10 in the form of a heavy-water moderated nuclear reactor in which steam is used as a coolant, steam generating means, a turbine 11 receiving part of the steam which is superheated in the heater 10, a steam condenser 12 and a feed water system.

The feed Water system comprises a plurality of feed water heaters 13, 14, 15, 16 connected in series from the outlet pipe 12a of the condenser 12 and a feed-water pump 17 at the entry to each of the heaters 13 to 16. The feed-water is heated in heater 13 by heat exchange with the moderator liquid owing in the reactor moderator liquid circuit 18, and is heated in the heaters 14, 15, 16 by steam fed to them by pipes 19a, 19b, 19e respectively of which pipes 19a, 19b lead from the turbine 11 and pipe 19e receives part of the vsteam leaving the heater 10.

The feed water leaving heater 16 is fed by pump 20 to branches 21, 22 leading to the steam generating means, the branch 22 containing a high pressure pump 23.

The steam generating means comprises a high pressure boiler 24 wherein water is evaporated in a water space and the resulting steam is superheated in a steam space by heat exchange with superheated steam fiowing in heat exchange coils 24a fed from a pipe 25 receiving superheated steam direct from the heater 10. Water is fed to the boiler 24 by pipe 22. Superheated steam so generated is fed from the boiler 24 through pipe 26 to a venturi device 27 to be expanded through a variable area sonic or supersonic nozzle 27a forming part of the venturi device, and the steam which has been used for heating in the boiler 24, is fed through pipe 24b into the venturi device at its throat 27b to be mixed with the steam expanded in nozzle 27a. The resulting quantity of steam is then compressed by flowing in the divergent portion 27e of the venturi device and ows from the device 27 through pipe 28a to an evaporator-attemperator tube 28 where water is sprayed into the steam from pipe 21 thereby to reduce the degree of superheat of the steam. The steam leaving the evaporator-attemperator tube 28 flows through pipe 29 to the heater 10. The device 27 is a steam ejector and is arranged to act as a thermal compressor, the high velocity jet of steam issuing from the nozzle 27a entraining steam from the pipe 24h and carrying it through the diffuser 27b, wherein velocity energy of the steam is converted into pressure energy, so that the steam entering the device from the pipe 24h is compressed. In this way a circulation of steam is maintained through the circuit comprising parts 28a, 29, 10, 30, 25, 24a, 24b, 27, without the use of mechanically driven pumps such as turbine driven pump-s or electrically driven pumps.

The superheated steam leaving the heater 10 through pipe 30 is divided between the pipes 25, 19e and the turbine inlet pipe 31. i

The output of the power plant just described can be varied by varying the area of the nozzle 27a. The nozzle will be reduced in size for starting the cycle and for lower power and/or shut down conditions.

The operating conditions may be in accordance with the following table:

Rate Quantity Operating of flow, ot heat, Plant partpressurc, million Btu/ll).

lbs/sq. in. lbs/hr. (Terzani: 1,010

.867 l, 534 .6023 1. 534 181B 50i) .6023 1,309 1818 l, 246 T841 1, 276 7841 1,295 .0829 500 S67 l, 219 0256 1, 534 2391 1, 534 D232 1y 417 0200 1, 294 1959 1, 037 (6.7% wet) 1959 G0 The plant described has a cycle eiciency of 36.5%.

The plant avoids the use of a rotary steam compressor and separate driving turbine or electric motor as are employed in well known cycles and also avoids the use of a large boiler with large steam heating coils. Also the plant has a higher cycle eiciency than known arrangements.

Instead of making the nozzle 27a of variable area, a valve may be provided in the high pressure steam line 26 to vary the flow into the venturi device.

We claim:

l. Steam generating plant comprising a heat exchanger wherein water is converted to steam at high pressure by heat exchange with superheated steam, which heat exchanger has an evaporation W path having a water inlet and a steam outlet and which heat exchanger also has a steam flow path with an inlet and an outlet, a steam heater wherein steam is superheated, said steam heater having an inlet thereto and an outlet therefrom, feed water means connected to deliver water to said inlet of the heater, steam supply means connected to deliver steam to said inlet of the heater, a first connection conveying superheated steam from the outlet of the steam heater to said inlet of the steam flow path, and means to maintain circulation of steam through the steam heater and the steam iiow path of the heat exchanger comprising a steam ow passage which is divergent in the direction of ow therethrough and having an inlet end and an outlet end, a high velocity nozzle connected to receive a rst quantity of said steam at high pressure from the steam outlet of said evaporation ow path and delivering steam at high velocity into said divergent flow passage at its inlet end, a second connection conveying a second and larger quantity of steam at a second pressure, which is substantially lower than said high pressure from the outlet of said steam ow path delivering into the inlet end of divergent low passage, the steam being compressed in said divergent passage by energy conversion, said outlet end of the divergent tiow passage being connected to deliver the steam to the steam inlet of the steam heater to be superheated therein.

2. Steam generating plant comprising a high-pressure boiler wherein water is converted to steam at high pressure by heat exchange into superheated steam having a water space and a steam space, a feed-water system connected to deliver water to the water space of the boiler, heating coils within the water space and within the steam space of the boiler, a heater having a steam Vinlet and a steam outlet, the steam outlet being connected to deliver heated steam to the heating coils, means to maintain circulation of steam through the heater and the boiler comprising a divergent steam ow passage having an inlet end and an outlet end, a high velocity nozzle connected to receive a first quantity of said `steam at high pressure flowing from the steam space of the boiler, a connection conveying a second a larger quantity of steam from the heating coils in the boiler to the divergent steam passage at a second pressure which is substantially lower than said high pressure, the steam being compressed in said divergent passage by energy conversion, said outlet end of the divergent ow passage being connected to deliver the steam to the steam inlet of the heater to be superheated therein, steam utilization means, and a delivery connection from the steam outlet of the heater conveying steam to said steam utilization means.

3. Steam generating plant according to claim 2, comprising a venturi device having a divergent portion forming said divergent flow passage, having said nozzle opening into said divergent portion at its smaller end, an adjustable valve member co-operating with the nozzle to vary its effective area, the heating coils being connected to deliver steam into said divergent portion at its smaller end.

4. Steam generating plant according to claim 2, comprising an evaporator-attemperator tube connected between the divergent ow passage and the inlet of the heater, and means connected to spray water into the evaporatorattemperator tube.

5. Steam generating plant according to claim 2, wherein the heater is a nuclear reactor in which the steam is employed as a coolant.

6. Steam generating plant according to claim 5 wherein the nuclear reactor is a liquid moderated reactor and comprises a liquid moderator circulation circuit, a feed water heater having flow paths connected `in said circulat-ion circuit and in said feed water system respectively whereby water is heated by the liquid moderator prior to delivery to the boiler.

7. Steam generating plant according to claim 2, comprising a feed water heater in said feed water system, and a steam tapping from said delivery connection to Said feed water heater whereby Water is heated by superheated steam tapped from the delivery connection prior to the water being delivered to the boiler.

References Cited in the tile of this patent UNITED STATES PATENTS 2,806,820 Wigner Sept. 17, 1957 2,861,033 Treshow Nov. 18, `1958 FOREIGN PATENTS 778,941 Great Britain July 17, 1957 1,027,338 Germany Apr. 3, 1958 

1. STEAM GENERATING PLANT COMPRISING A HEAT EXCHANGER WHEREIN WATER IS CONVERTED TO STEAM AT HIGH PRESSURE BY HEAT EXCHANGE WITH SUPERHEATED STEAM, WHICH HEAT EXCHANGER HAS AN EVAPORTION FLOW PATH HAVING A WATER INLET AND A STREAM OUTLET AND WHICH HEAT EXCHANGER ALSO HAS A STEAM FLOW PATH WITH AN INLET AND AN OUTLET, A STEAM HEATER WHEREIN STEAM IS SUPERHEATED, SAID STEAM HEATER HAVING AN INLET THERETO AND AN OUTLET THEREFROM, FEED WATER MEANS CONNECTED TO DELIVER WATER TO SAID INLET OF THE HEATER, STEAM SUPPLY MEANS CONNECTED TO DELIVER STEAM TO SAID INLET OF THE HEATER, A FIRST CONNECTION CONVEYING SUPERHEATED STEAM FROM THE OUTLET OF THE STEAM HEATER TO SAID INLET OF THE STEAM FLOW PATH, AND MEANS TO MAINTAIN CIRCULATION OF STEAM THROUGH THE STEAM HEATER AND THE STEAM FLOW PATH OF THE HEAT EXCHANGER COMPRISING A STEAM FLOW PASSAGE WHICH IS DIVERGENT IN THE DIRECTION OF FLOW THERETHROUGH AND HAVING AN INLET END AND AN OUTLET END, A HIGH VELOCITY NOZZLE CONNECTED TO RECEIVE A FIRST QUANTITY OF SAID STEAM AT HIGH PRESSURE FROM THE STEAM OUTLET OF SAID EVAPORATION FLOW PATH AND DELIVERING STEAM AT HIGH VELOCITY INTO SAID DIVERGENT FLOW PASSAGE AT ITS INLET END, A SECOND CONNECTION CONVEYING A SECOND AND LARGER QUANTITY OF STEAM AT A SECOND PRESSURE, WHICH IS SUBSTANTIALLY LOWER THAN SAID HIGH PRESSURE FROM THE OUTLET OF SAID STEAM FLOW PATH DELIVERING INTO THE INLET END OF DIVERGENT FLOW PASSAGE, THE STEAM BEING COMPRESSED IN SAID DIVERGENT PASSAGE BY ENERGY CONVERSION, SAID OUTLET END OF THE DIVERGENT FLOW PASSAGE BEING CONNECTED TO DELIVER THE STEAM TO THE STEAM INLET OF THE STEAM HEATER TO BE SUPERHEATED THEREIN. 